Cardiac arrhythmia is an abnormality in the timing or pattern of the heartbeat. Atrial tachyarrhythmia is a cardiac arrhythmia characterized by abnormally fast atrial rate, and can include various types of arrhythmias including atrial fibrillation, atrial flutter, atrial tachycardia, supraventricular tachycardia, among others. Atrial fibrillation (AF) is the most common clinical arrhythmia, and accounts for approximately one third of admissions resulting from cardiac rhythm disturbances. During AF, the normal regular sinus rhythm is overwhelmed by disorganized electrical pulses originated from regions in or near an atrium. This can lead to irregular conductions to ventricles, causing inappropriately fast and irregular heart rate. One type of AF is paroxysmal AF which may last from minutes to days before it stops by itself. Another type known as persistent AF may last for over a week and typically requires medication or other treatment to revert to normal sinus rhythm. The third type, permanent AF, is a condition where a normal heart rhythm cannot be restored with treatment. Persistent AF can become more frequent and result in permanent AF.
Congestive heart failure (CHF or HF) is another major cardiovascular epidemic and affects many people in the United States alone. CHF is the loss of pumping power of the heart, resulting in the inability to deliver enough blood to meet the demands of peripheral tissues. CHF patients typically have enlarged heart with weakened cardiac muscles, resulting in reduced contractility and poor cardiac output of blood. CHF can affect the left heart, right heart or both sides of the heart, resulting in non-simultaneous contractions of the left ventricle and contractions of the right ventricle. Such non-simultaneous contractions, also known as dyssynchroncy between the left and right ventricles, can further decrease the pumping efficiency of the heart.
There is a close pathophysiological relationship between AF and CHF. A large percentage of CHF patients may experience AF or other types of atrial tachyarrhythmias. AF may facilitate the development or progression of CHF, and CHF can increase the risk for the development of AF. The prevalence of AF in patients with CHF increased in parallel with the severity of CHF.